Neurochemicals modify the electrical activity of cells or neurons, induce gene and protein expression, which lead to short and long-term modifications in the phenotype of the neuron or cell. Thus, defining the neurochemical profile of specific cells and neurons is essential to understanding physiological and pathological functions that underlie normal development and aging in health and disease. Recent advances in micro and nanobiosensing technologies has provided an avenue to measure real-time release of neurochemical released from neurons and cells. ATP is released from neurons in the central and peripheral nervous system, and mediates fast-synaptic transmission via binding to P2X ion-gated channels. The peripheral arterial chemoreceptors in the carotid body are critical in regulating ventilation and circulatory responses to changes in oxygen tension, and they provide essential sensory input during early development to stabilize and maintain breathing throughout life. Maturation of hypoxic chemosensitivity occurs within in the first several weeks of mammalian postnatal development. We hypothesize that increase release of ATP from oxygen sensing cells in the peripheral arterial chemoreceptors may operative in mediating the development of hypoxic chemosensitivity. In response to the program announcement (PA, 03-058) for exploratory/developmental bioengineering research grants (EBRG), we aim to 1) further develop a novel dual enzyme-based amperometric microbiosensor (tip diameter 5-10 mcirons) that can measure ATP release across a wide range of physiological conditions in solution, and 2) measure ATP release from the superfused rat carotid body thereby establishing the stimulus-response profile of ATP release from the carotid body during postnatal maturation. These studies will be done in collaboration with colleagues at Georgia Institutute of Technology, who have already developed the prototype of the microbiosensor to be used in experiments outlined in this proposal. Since synaptic transmission is the core elementary process in the function of the peripheral and central nervous system, and ATP is an important molecule involved in this process, we believe that successful fabrication of this microbiosenor will allow for general application to multiple experimental paradigms that interrogates cellular and molecular mechanisms that meditate synaptic transmission during development and aging. Adenosine triphosphate (ATP) is an essential molecule that allows nerves to communicate with each other. With the correct tools, (microbiosensors) we can measure this small molecule as it is released from tissues and neurons. This grant proposes to develop a microbiosensor to measure the release of ATP from the carotid body to understand how the newborn develops an adequate breathing response to changes in oxygen concentration. [unreadable] [unreadable]